A portable electronic device such as a smartphone or a tablet terminal allows a user to enter a character or a number with a touch of a finger on a software keyboard displayed on a touch screen. The software keyboard has operational restrictions because the display area of the touch screen is small compared with that of a hardware keyboard made up of physical keys used in a laptop personal computer or with a desktop personal computer.
Commonly, when a software keyboard is displayed on a small touch screen like that of a smartphone, many keys are displayed concurrently, e.g., like the QWERTY keyboard layout, thus an application screen such as a mailer screen or a browser screen are hidden, and hence restricted in operating and browsing the application screen while performing input. Further, when the size of each key is reduced to enlarge the display area of the application screen, the user may select an adjacent key with a finger, resulting in wasting time until a target key is confirmed.
Although the number of keys displayed can be reduced to enlarge each key like in a flick operation, this requires multiple operations until the target key is confirmed. Further, in the case where a user wants to operate a smartphone while holding it in one hand when, for example, the user is holding onto a strap in a train or carrying baggage in the other hand. A user cannot perform an input operation easily on conventional smartphones at this time of unstable holding because of possible unintended touch operations on the application screen displayed on the touch screen.